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The ALMA Spectroscopic Survey Large Program: The Infrared Excess of z = 1.5–10 UV-selected Galaxies and the Implied High-redshift Star Formation History

Bouwens, Rychard; González-López, Jorge; Aravena, Manuel; Decarli, Roberto; Novak, Mladen; Stefanon, Mauro; Walter, Fabian; Boogaard, Leindert; Carilli, Chris; Dudzevičiūtė, Ugnė; Smail, Ian; Daddi, Emanuele; da Cunha, Elisabete; Ivison, Rob; Nanayakkara, Themiya; Cortes, Paulo; Cox, Pierre; Inami, Hanae; Oesch, Pascal; Popping, Gergö; Riechers, Dominik; van der Werf, Paul; Weiss, Axel; Fudamoto, Yoshi; Wagg, Jeff

The ALMA Spectroscopic Survey Large Program: The Infrared Excess of z = 1.5–10 UV-selected Galaxies and the Implied High-redshift Star Formation History Thumbnail


Authors

Rychard Bouwens

Jorge González-López

Manuel Aravena

Roberto Decarli

Mladen Novak

Mauro Stefanon

Fabian Walter

Leindert Boogaard

Chris Carilli

Emanuele Daddi

Elisabete da Cunha

Rob Ivison

Themiya Nanayakkara

Paulo Cortes

Pierre Cox

Hanae Inami

Pascal Oesch

Gergö Popping

Dominik Riechers

Paul van der Werf

Axel Weiss

Yoshi Fudamoto

Jeff Wagg



Abstract

We make use of sensitive (9.3 μJy beam−1 rms) 1.2 mm continuum observations from the Atacama Large Millimeter/submillimeter Array (ALMA) Spectroscopic Survey in the Hubble Ultra-Deep Field (ASPECS) large program to probe dust-enshrouded star formation from 1362 Lyman-break galaxies spanning the redshift range z = 1.5–10 (to ~7–28 M ⊙ yr−1 at 4σ over the entire range). We find that the fraction of ALMA-detected galaxies in our z = 1.5–10 samples increases steeply with stellar mass, with the detection fraction rising from 0% at 109.0 M ⊙ to ${85}_{-18}^{+9}$% at >1010 M ⊙. Moreover, on stacking all 1253 low-mass (<109.25 M ⊙) galaxies over the ASPECS footprint, we find a mean continuum flux of −0.1 ± 0.4 μJy beam−1, implying a hard upper limit on the obscured star formation rate of <0.6 M ⊙ yr−1 (4σ) in a typical low-mass galaxy. The correlation between the infrared excess (IRX) of UV-selected galaxies (L IR/L UV) and the UV-continuum slope is also seen in our ASPECS data and shows consistency with a Calzetti-like relation at >${10}^{9.5}\,{M}_{\odot }$ and an SMC-like relation at lower masses. Using stellar mass and β measurements for z ~ 2 galaxies over the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we derive a new empirical relation between β and stellar mass and then use this correlation to show that our IRX–β and IRX–stellar mass relations are consistent with each other. We then use these constraints to express the IRX as a bivariate function of β and stellar mass. Finally, we present updated estimates of star formation rate density determinations at z > 3, leveraging present improvements in the measured IRX and recent probes of ultraluminous far-IR galaxies at z > 2.

Citation

Bouwens, R., González-López, J., Aravena, M., Decarli, R., Novak, M., Stefanon, M., …Wagg, J. (2020). The ALMA Spectroscopic Survey Large Program: The Infrared Excess of z = 1.5–10 UV-selected Galaxies and the Implied High-redshift Star Formation History. Astrophysical Journal, 902(2), Article 112. https://doi.org/10.3847/1538-4357/abb830

Journal Article Type Article
Acceptance Date Aug 30, 2020
Online Publication Date Oct 19, 2020
Publication Date 2020-10
Deposit Date Nov 4, 2020
Publicly Available Date Nov 5, 2020
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 902
Issue 2
Article Number 112
DOI https://doi.org/10.3847/1538-4357/abb830

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Copyright Statement
© 2020. The American Astronomical Society. All rights reserved.





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